/*
 * @(#)KeyUsageExtension.java	1.23 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package sun.security.x509;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Array;
import java.util.Enumeration;

import sun.security.util.*;

/**
 * Represent the Key Usage Extension.
 *
 * <p>This extension, if present, defines the purpose (e.g., encipherment,
 * signature, certificate signing) of the key contained in the certificate.
 * The usage restriction might be employed when a multipurpose key is to be
 * restricted (e.g., when an RSA key should be used only for signing or only
 * for key encipherment).
 *
 * @author Amit Kapoor
 * @author Hemma Prafullchandra
 * @version 1.16
 * @see Extension
 * @see CertAttrSet
 */
public class KeyUsageExtension extends Extension
implements CertAttrSet {

    /**
     * Identifier for this attribute, to be used with the
     * get, set, delete methods of Certificate, x509 type.
     */
    public static final String IDENT = "x509.info.extensions.KeyUsage";
    /**
     * Attribute names.
     */
    public static final String NAME = "KeyUsage";
    public static final String DIGITAL_SIGNATURE = "digital_signature";
    public static final String NON_REPUDIATION = "non_repudiation";
    public static final String KEY_ENCIPHERMENT = "key_encipherment";
    public static final String DATA_ENCIPHERMENT = "data_encipherment";
    public static final String KEY_AGREEMENT = "key_agreement";
    public static final String KEY_CERTSIGN = "key_certsign";
    public static final String CRL_SIGN = "crl_sign";
    public static final String ENCIPHER_ONLY = "encipher_only";
    public static final String DECIPHER_ONLY = "decipher_only";

    // Private data members
    private boolean[] bitString;

    // Encode this extension value
    private void encodeThis() throws IOException {
        DerOutputStream os = new DerOutputStream();
        os.putUnalignedBitString(new BitArray(this.bitString));
        this.extensionValue = os.toByteArray();
    }

    /**
     * Check if bit is set.
     *
     * @param position the position in the bit string to check.
     */
    private boolean isSet(int position) {
        return bitString[position];
    }

    /**
     * Set the bit at the specified position.
     */
    private void set(int position, boolean val) {
	// enlarge bitString if necessary
        if (position >= bitString.length) {
            boolean[] tmp = new boolean[position+1];
            System.arraycopy(bitString, 0, tmp, 0, bitString.length);
            bitString = tmp;
        }
	bitString[position] = val;
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(byte[] bitString) throws IOException {
        this.bitString =
	    new BitArray(bitString.length*8,bitString).toBooleanArray();
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(boolean[] bitString) throws IOException {
        this.bitString = bitString;
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create a KeyUsageExtension with the passed bit settings. The criticality
     * is set to true.
     *
     * @param bitString the bits to be set for the extension.
     */
    public KeyUsageExtension(BitArray bitString) throws IOException {
        this.bitString = bitString.toBooleanArray();
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = true;
        encodeThis();
    }

    /**
     * Create the extension from the passed DER encoded value of the same.
     * The DER encoded value may be wrapped in an OCTET STRING.
     *
     * @param critical true if the extension is to be treated as critical.
     * @param value Array of DER encoded bytes of the actual value (possibly
     * wrapped in an OCTET STRING).
     * @exception IOException on error.
     */
    public KeyUsageExtension(Boolean critical, Object value)
    throws IOException {
        this.extensionId = PKIXExtensions.KeyUsage_Id;
        this.critical = critical.booleanValue();
        /*
         * The following check should be activated again after
         * the PKIX profiling work becomes standard and the check
         * is not a barrier to interoperability !
         * if (!this.critical) {
         *   throw new IOException("KeyUsageExtension not marked critical,"
         *                         + " invalid profile.");
         * }
         */
        int len = Array.getLength(value);
	byte[] extValue = new byte[len];
	for (int i = 0; i < len; i++) {
	    extValue[i] = Array.getByte(value, i);
	}
	if (extValue[0] == DerValue.tag_OctetString) {
	    this.extensionValue = new DerValue(extValue).getOctetString();
	} else {
	    this.extensionValue = extValue;
	}
	DerValue val = new DerValue(this.extensionValue);
	this.bitString = val.getUnalignedBitString().toBooleanArray();
    }

    /**
     * Create a default key usage.
     */
    public KeyUsageExtension() {
        extensionId = PKIXExtensions.KeyUsage_Id;
        critical = true;
        bitString = new boolean[0];
    }

    /**
     * Set the attribute value.
     */
    public void set(String name, Object obj) throws IOException {
        if (!(obj instanceof Boolean)) {
	    throw new IOException("Attribute must be of type Boolean.");
	}
	boolean val = ((Boolean)obj).booleanValue();
	if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
	    set(0,val);
	} else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
	    set(1,val);
	} else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
	    set(2,val);
	} else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
	    set(3,val);
	} else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
	    set(4,val);
	} else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
	    set(5,val);
	} else if (name.equalsIgnoreCase(CRL_SIGN)) {
	    set(6,val);
	} else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
	    set(7,val);
	} else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
	    set(8,val);
	} else {
	  throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
	}
        encodeThis();
    }

    /**
     * Get the attribute value.
     */
    public Object get(String name) throws IOException {
	if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
	    return new Boolean(isSet(0));
	} else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
	    return new Boolean(isSet(1));
	} else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
	    return new Boolean(isSet(2));
	} else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
	    return new Boolean(isSet(3));
	} else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
	    return new Boolean(isSet(4));
	} else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
	    return new Boolean(isSet(5));
	} else if (name.equalsIgnoreCase(CRL_SIGN)) {
	    return new Boolean(isSet(6));
	} else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
	    return new Boolean(isSet(7));
	} else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
	    return new Boolean(isSet(8));
	} else {
	  throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
	}
    }

    /**
     * Delete the attribute value.
     */
    public void delete(String name) throws IOException {
	if (name.equalsIgnoreCase(DIGITAL_SIGNATURE)) {
	    set(0,false);
	} else if (name.equalsIgnoreCase(NON_REPUDIATION)) {
	    set(1,false);
	} else if (name.equalsIgnoreCase(KEY_ENCIPHERMENT)) {
	    set(2,false);
	} else if (name.equalsIgnoreCase(DATA_ENCIPHERMENT)) {
	    set(3,false);
	} else if (name.equalsIgnoreCase(KEY_AGREEMENT)) {
	    set(4,false);
	} else if (name.equalsIgnoreCase(KEY_CERTSIGN)) {
	    set(5,false);
	} else if (name.equalsIgnoreCase(CRL_SIGN)) {
	    set(6,false);
	} else if (name.equalsIgnoreCase(ENCIPHER_ONLY)) {
	    set(7,false);
	} else if (name.equalsIgnoreCase(DECIPHER_ONLY)) {
	    set(8,false);
	} else {
	  throw new IOException("Attribute name not recognized by"
                                + " CertAttrSet:KeyUsage.");
	}
        encodeThis();
    }

    /**
     * Returns a printable representation of the KeyUsage.
     */
    public String toString() {
        String s = super.toString() + "KeyUsage [\n";

	try {
	    if (isSet(0)) {
		s += "  DigitalSignature\n";
	    }
	    if (isSet(1)) {
		s += "  Non_repudiation\n";
	    }
	    if (isSet(2)) {
		s += "  Key_Encipherment\n";
	    }
	    if (isSet(3)) {
		s += "  Data_Encipherment\n";
	    }
	    if (isSet(4)) {
		s += "  Key_Agreement\n";
	    }
	    if (isSet(5)) {
		s += "  Key_CertSign\n";
	    }
	    if (isSet(6)) {
		s += "  Crl_Sign\n";
	    }
	    if (isSet(7)) {
		s += "  Encipher_Only\n";
	    }
	    if (isSet(8)) {
		s += "  Decipher_Only\n";
	    }
	} catch (ArrayIndexOutOfBoundsException ex) {}

        s += "]\n";

        return (s);
    }

    /**
     * Decode the extension from the InputStream.
     *
     * @param in the InputStream to unmarshal the contents from.
     * @exception IOException on decoding or validity errors.
     */
    public void decode(InputStream in) throws IOException {
        throw new IOException("Method not to be called directly.");
    }

    /**
     * Write the extension to the DerOutputStream.
     *
     * @param out the DerOutputStream to write the extension to.
     * @exception IOException on encoding errors.
     */
    public void encode(OutputStream out) throws IOException {
       DerOutputStream	tmp = new DerOutputStream();

       if (this.extensionValue == null) {
           this.extensionId = PKIXExtensions.KeyUsage_Id;
           this.critical = true;
           encodeThis();
       }
       super.encode(tmp);
       out.write(tmp.toByteArray());
    }

    /**
     * Return an enumeration of names of attributes existing within this
     * attribute.
     */
    public Enumeration getElements() {
        AttributeNameEnumeration elements = new AttributeNameEnumeration();
        elements.addElement(DIGITAL_SIGNATURE);
        elements.addElement(NON_REPUDIATION);
        elements.addElement(KEY_ENCIPHERMENT);
        elements.addElement(DATA_ENCIPHERMENT);
        elements.addElement(KEY_AGREEMENT);
        elements.addElement(KEY_CERTSIGN);
        elements.addElement(CRL_SIGN);
        elements.addElement(ENCIPHER_ONLY);
        elements.addElement(DECIPHER_ONLY);

	return (elements.elements());
    }


    public boolean[] getBits() {
	return (boolean[]) bitString.clone();
    }

    /**
     * Return the name of this attribute.
     */
    public String getName() {
        return (NAME);
    }
}
